Doctrine for the Body of Christ comes from Jesus.
Jesus was back in Heaven 40 days after He rose from the dead.
Before He ascended, He told the remaining Apostles that """"""He had many things to tell them... but they were not ready to hear/receive/understand.""""""
AFter Jesus was back in Heaven, this happened.
"Paul is a chosen vessel unto me"...
To do what?
A.) Teach all that Jesus said, that the other Apostles still needed to learn, as well as give the Body of Christ "church Doctrine".
This is why Peter said that Paul's LETTERS, are "Scripture", as Paul's LETTERS became MOST of the NT Epistles.
Right now, the world is in "the time of the Gentiles", and this will end... and Paul is the "Apostle to the Gentiles"..
HE is our Teacher, and that is why He told us..
1 Corinthians 11:1